1. Field of the Invention
The present invention relates to a remote control wiring mechanism in which an on-off state of a switch is reflected in the switching of a relay by transmitting a transmission signal including on-off information of the switch through a signal line.
2. Description of the Related Art
Conventionally, in order to remotely monitor and control loads, there is known a technology of transmitting a transmission signal including on-off information of a switch through a signal line and switching a relay for turning on and off a load power in accordance with the transmission signal. The switch includes automatic switches for outputting a contact signal corresponding to sensed results of various sensors, as well as switches manipulated by persons.
As such a type of remote monitoring and control system, there is a known a central control system having a monitoring unit 11 having switches 13 and a control unit 12 fitted with relays 14 for turning on and off loads as terminal devices and having a transmission unit 10 as a central device, for example, as shown in FIG. 11 (see Patent Document 1). The transmission unit 10, the monitoring unit 11, and the control unit 12 are connected through two-wire signal lines 15. The transmission unit 10 identifies the monitoring unit 11 and the control unit 12 by using addresses set to the monitoring unit 11 and the control unit 12. The transmission unit 10, the monitoring unit 11, and the control unit 12 are all composed of a microcomputer.
The transmission unit 10 includes a memory storing a control table, which is a data table in which monitoring units 11 and control units 12 correspond to each other in accordance with the addresses. When the on-off information of switches 13 provided in any one monitoring unit 11 is sent to the transmission unit 10 by using a transmission signal (time-divisional multiple transmission signal), an instruction of switching the relay 14 using the transmission signal is transmitted to the control unit 12 corresponding to the monitoring unit 11 by the control table and the relay 14 of the control unit 12 is switched in accordance with the instruction. The instruction of switching the relay 14 reflects the on-off information of the switch 13. Accordingly, although the transmission unit 10 is interposed between the monitoring unit 11 and the control unit 12, the on-off state of the switch 13 is reflected in the switching of the relay 14 by transmitting the transmission signal including the on-off information of the switch 13 through the signal lines 15. One monitoring unit 11 can identify four switches 13 in maximum and one control unit 12 can identify four relays 14 in maximum. The control table provided in the transmission unit 10 makes it possible for the switches 13 and the relays 14 to correspond to each other in a unit of circuits. In the control table, the switches 13 and the relays 14 can be connected in 1:plural, as well as in 1:1.
When lighting instruments as a load are turned on or off using the relays 14, the transmission unit 10 can perform individual control that one lighting instrument is turned on and off with one switch and collective control that a plurality of lighting instruments is turned on and off with one switch. In other words, the individual control means that one circuit of load is controlled by one instruction and the collective control means that plural circuits of loads are controlled by one instruction. The collective control is classified into group control that the range of loads to be controlled is made to correspond to a switch and the loads in the range are turned on and off at a time by means of manipulation of the switch and pattern control that the range of addresses of the loads to be controlled and the on and off states of the loads are made to correspond to a switch and the loads in the range are individually turned on and off by means of the switch.
In order to perform the group control or the pattern control, the group number or the pattern number corresponding to the switch for performing the group control or the pattern control is made to correspond to the addresses of the loads in the range to be controlled in the control table provided in the transmission unit 10. When the switch for the group control or the pattern control is manipulated, the addresses of the loads to be controlled are developed by referring to the control table in the transmission unit 10, the on and off states of the loads are determined, and then an instruction is given to the control unit 12 having the address obtained by referring to the control table.
In the remote monitoring and control system, the transmission unit 10 periodically transmits the transmission signal to the signal lines 15, where a bipolar pulse width modulation signal of ±24V is used as the transmission signal. The monitoring unit 11 and the control unit 12 secure an internal power source by full-wave rectifying the transmission signal. The transmission unit 10 is supplied with commercial power. On the other hand, the control unit 12 controlling the relay 14 requires a power supply for driving the relay 14 and the relay 14 controlling the load such as a lighting instrument requires a remote control transformer 16 which is a step-down transformer in order to obtain the AC voltage of 24V for driving the relay from the commercial supply voltage (for example, AC voltage of 100V). That is, it is necessary to connect the control unit 12 and the relay 14 to the remote control transformer 16 through a driving power line 17.
Operations of the transmission unit 10, the monitoring unit 11, and the control unit 12 are briefly described. The transmission unit 10 performs normal polling that a transmission signal periodically converted from an address is periodically transmitted to the signal line 15. As the transmission signal, a start pulse indicating the start of signal transmission, mode data indicating a signal mode, address data including addresses (addresses of the monitoring unit 11 or the control unit 12) for individually calling out the monitoring unit 11 or the control unit 12, control data (including information for identifying circuits of loads) transmitting control data for controlling the loads, checksum data for detecting transmission errors, bipolar (±24V) signals including a signal returning period which is a time slot for receiving returned signals from the monitoring unit 11 or the control unit 12 are used.
When a monitoring instruction is input by means of manipulation of a switch in any one monitoring unit 11, the monitoring unit 11 transmits an interrupt signal synchronized with the start pulse of the transmission signal to the signal lines 15. The monitoring unit 11 generating the interrupt signal becomes a latch state in which an interrupt flag is set. On the other hand, when the transmission unit 10 detects the interrupt signal, the transmission unit 10 sends out the transmission data including the mode data of a search mode. When the monitoring unit 11 of the latched state receives the transmission signal of the search mode, the monitoring unit 11 sends back the address during the signal-returning period. The transmission unit 10 receiving the address identifies the monitoring terminal 11 generating the interrupt signal by transmitting the transmission signal requesting the return of the latched state to the monitoring unit 11 of the address and confirming the latched state. When the monitoring unit 11 generating the interrupt signal is identified, the transmission signal releasing the latched state is transmitted and the latched state of the monitoring unit 11 is released.
The transmission unit 10 receives the request from the monitoring unit 11 through the above-mentioned operations, the transmission unit 10 requests the control unit 12 corresponding to the monitoring unit 11 to control the load in accordance with the control table. Next, the transmission unit 10 sends out the transmission signal for confirming the operation state of the relay 14 provided in the control unit 12 and receives the operation state of the relay 14 from the control unit 12. The operation state of the relay 4 received from the control terminal is confirmed by the transmission unit 10. When the operation state of the relay 14 is an off state, the transmission unit 10 transmits the transmission signal indicating that the operation state is inverted to an on state to the monitoring unit 11 of which the switch 13 is manipulated and transmits the transmission signal indicating the same control details as described above to the control unit 12. It is intended to reflect the same control details of the control unit 12 in the display state of a display lamp for displaying an on or off state that the transmission signal indicating the same control details for the control unit 12 is transmitted to the monitoring unit 11. The control unit 12 receiving the transmission signal indicating the operation state sends back an echo back for confirming the reception thereof.
As described above, the switch 13 (the address of the monitoring unit 11 and the circuit of the switch 13) of the transmission unit 10 is combined into the control table and the transmission signal indicating the control of the relay 14 is transmitted to the control unit 12 having the relay 14 of which the correspondence with the switch 13. In this way, the on-off information of the switch 13 can be reflected in the switching of the relay 14.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2000-10694
As described above, since the transmission unit 10, the monitoring unit 11, the control unit 12, the relay 14, and the remote control transformer 16 are required for constructing the remote monitoring and control system, there are problems that the number of constituent elements is large and that the work of selecting the elements at the time of constructing the remote monitoring and control system is troublesome and requires skill. Since it is necessary to connect the transmission unit 10, the monitoring unit 11, and the control unit 12 to the signal lines 15 and connect the control unit 12 and the relay 14 to the remote control transformer 16 through the driving power lines 17, the connection work of the signal lines 15 and the driving power lines 17 is troublesome. In addition, when the plural circuits of relays 14 are controlled by the control unit 12, the connecting relations among the control unit 12, the relays 14, and the remote control transformer 16 are complex, thereby making troublesome the connection work.